Counting number of vowels in a string with JavaScript

Question

I\'m using basic JavaScript to count the number of vowels in a string. The below code works but I would like to have it cleaned up a bit. Would using .includes()

Answer 1

As the introduction of forEach in ES5 this could be achieved in a functional approach, in a more compact way, and also have the count for each vowel and store that count in an Object.

function vowelCount(str){
  let splitString=str.split('');
  let obj={};
  let vowels="aeiou";
  splitString.forEach((letter)=>{
    if(vowels.indexOf(letter.toLowerCase())!==-1){
      if(letter in obj){
        obj[letter]++;
      }else{
        obj[letter]=1;
      }
    }   

 });
 return obj;    
}